There are a number of conventional processes for packaging integrated circuit (IC) dice. In many applications it is desirable to form solder bumps directly on the active surface of an IC die. Typically, the solder bumps are formed on the active surface of the wafer before the individual dice are singulated from a wafer. When the resulting die is mounted onto a substrate or other appropriate carrier, the solder bumps may be reflowed to create electrical connections between the die and substrate. This style of electrically connecting IC dice is often called “flip-chip” mounting because the die is generally “flipped” in order to position the solder bumps on its active surface onto associated contacts on the surface of the substrate to which the die is to be attached. As the size constraints placed on IC dice and packages get smaller and smaller, there are an increasing number of applications in which flip-chip mounting is desirable.
The packaging of IC devices configured for use in power applications (e.g., IC devices designed to transport and/or regulate electrical power) often presents greater challenges than those encountered when packaging conventional IC dice not configured or intended for use in power applications. Generally, power packages include dice having lines that carry much higher currents (and sometimes higher voltages) than typical semiconductor devices. At the same time, many power devices also have signal lines that must be able to accommodate relatively high speeds. Those familiar with the art will appreciated that in most cases power IC devices and high speed IC devices are packaged separately. Due to a number of constraints, flip-chip mounting and packaging techniques have not been widely used for power applications. Accordingly, although existing packaging techniques work well, there are continuing efforts to develop even more efficient designs and methods for surface mounting IC components in order to accommodate a variety of different application requirements including the unique challenges of power applications.